1. Field of the Invention
The present invention relates to a process for gentle long-lasting shaping (permanent waving or uncurling) of human hair whereby the hair-shaping agent is rinsed off before the winding or the use of other fastening means or, in the case of uncurling, before combing.
2. Prior Art
The shaping of hair by the conventional permanent waving method is achieved in that prewashed and thus swollen, but not previously reduced, hair is bent under tension (tensile stress) by use of a shaping device, particularly a curler, and treated with the permanent wave reducing agent. The permanent wave agent is allowed to act on the wound hair for 3 to 30 min, depending on the hair shaping desired, until reshaping has taken place. After exposure of the hair to the permanent wave agent, excess reducing agent is removed with water or by use of an acidic rinse. Despite thorough rinsing, however, a small amount of reducing agent remains on the hair surface and inside the hair (for more details see SOFW Journal 123, pp. 79-83, 1997). After rinsing, the cystine disulfide bonds are reformed by use of a fixative, namely of an oxidant-containing agent.
In the conventional permanent waving method, as a rule, the hair-dresser determines the time of exposure to the reducing agent-containing shaping agent by assessing the degree of shaping with several test curlers. The hair-dresser is often uncertain and extends the exposure time to ensure adequate shaping. An excessively long exposure, however, results in an overtreatment of the hair, particularly along the hair shaft and at the hair tips. This is known as overcurling. It manifests itself, on the one hand, visually, in that the curls along the shaft and at the tip of the hair are very small (frizzing), and, on the other, in that the overcurled hair region feels limp despite the frizzing and shows inadequate elasticity. Such overcurling effects cause irreversible, permanent hair damage.
German Patent Application G8775 IVa/30h published on 10-4-1956 discloses a method for permanent shaping of keratin fibers whereby the keratin fibers, wound and exposed to a reactive reducing solution, are rinsed with water after a period of time that is insufficient for conventional shaping, and the fibers are then left on the curlers for 2 to 3.5 hours to expose them to air oxidation. The use of a chemical fixing agent is not required. This time-consuming and for the customer troublesome method has not been accepted by hair-dressers.
DE-A-36 10 394 discloses a process for shaping hair whereby the hair is treated at pH 6.0 to 7.5 with a hair-shaping shampoo containing from 1.5 to 12 wt % of at least one surfactant and from 2 to 15 wt % of at least one hair keratin-reducing substance. The hair is then rinsed with water, optionally wound onto curlers, optionally rinsed with water and then subjected to an oxidative aftertreatment.
Currently used shaping processes have in common the feature that the reducing permanent shaping agent acts on the hair in undiminished strength for a period of time required for hair shaping and thus, particularly after repeated hair shaping, causes irreversible hair damage, professionally referred to as "overcurling". The negative consequences for the hair are poor elasticity and springiness, reduced tensile strength, poor hair-styling properties and reduced sheen.